Device for the manufacture of dental crowns.



J. M. GILMORE. DEVICE FOR THE MANUFACTURE OF DENTAL GROWNS. APPLICATIONFILED SEPT. 30..1910.

999,366. Patented Aug. 1,1911.

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COLUHBIA PLANOGUPH 80 WASHINLITUN, D. C-

J. M. GILMORE. DEVICE FOR THE MANUFACTURE or DENTAL cnowus.

APPLICATION FILED SEPT. 30, 1910.

Patented Aug. 1, 1911.

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JOHN M. GILMORE, OF CHICAGO, ILLINOIS.

DEVICE FOR THE MANUFACTURE OF DENTAL CROVVNS.

Application filed September 30, 1910.

To all whom it may concern:

Be itknown that I, JOHN M. Gimronn, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a new and useful Improvement in Devices for the Manufacture ofDental Crowns, of which the follow ing is a specification.

My invention relates particularly to devices for manufacturing crownsfor teeth, either for capping them, providing dummy crowns forbridge-work, or producing porcelain shell-crowns.

The manufacture of crowns especially for capping teeth, as hithertopracticed, is not only expensive and requires a relatively high degreeof skill, but is a long and tedious operation and productive of greatpain and discomfort to the patient. The most commonly practiced methodinvolves the formation of a band and cusp in separate parts and thesubsequent uniting of the same. this method presenting among the mostserious objections, the great amount of time involved in the operation,the fitting and refitting of the hand, both before and after the cusp isunited to it, and the necessity, which occurs in almost every case, ofshap ing the cusps, which are of relatively thick metal, by filing orpolishing the metal to cause the occlusal portions of the cusp topresent the desired shape and size, with consequent loss of time andwaste of precious metal.

My object is to provide improvements in devices for the manufacture ofcrowns to the end of facilitating and reducing the time required fortheir manufacture, cheapening the cost thereof, and sparing the patientpain and discomfort.

My invention is illustrated in the accompanying drawings, in whichFigure 1 is a perspective View of a former and plunger employed togetherwith a cap or thimble from which a crown can be made, the parts referredto being shown in their relative positions but unassembleol. Fig 2. is asimilar view of the parts illustrated in Fig. 1 showing them inassembled condition preparatory to the forming of the crown. Fig. 3 is aplan view of a portion of a dieplate commonly employed by dentists forshaping cusps of crowns, and which may be used in connection with theparts shown in Figs. 1 and 2. Fig. 4 is a view in elevation of the partsillustrated in Fig. 2, the former Specification of Letters Patent.

Patented Aug. 1, 1911.

Serial No. 584,614.

and cap being shown in section, this view showing the positions theparts assume after the swaging operation for shaping the cap into acrown has been performed. Fig. 5 is a view similar to Fig. 1, showingthe condition of the former with relation to the formed crown after theplunger has been removed. Fig. 6 is a perspective view of the finishedcrown. Fig. 7 is a plan view of a sheet metal blank from which a cap tobe formed into a crown may be made. Fig. 8 is a perspective View of thecap formed from the sheet of Fig. 7. Fig. 9 is a similar view of a crownformed from the cap of Fig. 8. Fig. 10 is a view like Fig. 1 of theformer and plunger employed, together with a tubesection from which acrown for supporting a porcelain facing may be made. Fig. 11 is a viewin elevation of the parts illustrated in Fig. 10, the former and capbeing shown in section, this view showing the positions the parts assumeafter the swaging operation for shaping the tube has been performed.Fig. 12 is a view like Fig. 1.1 showing the condition of the former withrelation to the formed crown after the plunger has been removed. Fig. 13is a perspective view of the crown formed by the devices of Fig. 10.Fig. 1 1 is a similar view of a porcelain facing. Fig. 15 is a view ofthe finished porcelain-faced crown. Fig. 16 is a view like that of Fig.1 showing the parts for forming the metal portion of a porcelain-facedcrown for a bicuspid. Fig. 17 is a view like Fig. 41 of the parts shownin Fig. 16, this view illustrating how these parts may be used inconnection with a die-plate for forming the crown. Fig. 18 is aperspective view of the metal portion of the crown formed from thedevices of Fig. 16; and Fig. 19, a perspective view of the finishedporcelain-faced crown.

For the purpose of illustrating my invention in its application to themanufacture of crowns wholly of metal, I have chosen to show it forforming crowns for posterior teeth, and more particularly bicuspids.

In carrying out my invention, as for in stance in the manufacture ofcrowns for bicuspids, I employ a former 20 open at both ends, one endbeing flared as illustrated at 21, and the other end, represented at 22,being shaped to conform to the contour of the sides of the perfectbicuspid. The end 22 of the former, which is preferably constructed ofthin metal, is formed of sections 23 united at the flared end of theformer, these sections being shown as four in number, though the numbermay be varied as desired. The former 20 is preferably so constructed asto cause its end 22 to be of the same shape, but slightly smaller thanthe smallest bicuspid, the sections23 being disconnected from each otheralong lines corresponding to the developmental lines of a tooth, inorder that the former in being expanded as hereinafter described willconform to standard bicuspids of all sizes. Cooperating with the former20 is a plunger 24: preferably constructed of metal and tapering towardone end as illustrated. The sides of the smaller end of the plunger areof approximately the same shape asthose of the end 22 of the former 20.

To construct a crown for a bicuspid, the operator first prepares thetooth to be crowned by removing the enamel. The circumference. of thestub of the tooth is then measured and a cap selected, which may be ofthe seamless variety illustrated at 25 in Fig. 1, or formed from a sheetof metal as hereinafter described, and which is of the same internalcircumference as the outer circumference of the tooth stub. The operatorthen inserts the end 22 of the former into the cap 25 and the plunger24: into the larger end of the former to the positions illustrated inFig. 2. The plunger 2% is then forced into the former 20 to cause thesections 23 of the latter to spread apart into close engagement with thewall of the cap 25, the portion of the crown which is to encircle thetooth remaining unstret-ched in this operation. This may be done byhand, as the metal of the cap which I prefer to employ is comparativelythin gold, or other suitable metal, and readily conforms to the shape ofthe end 22 of the former 20. The operator may use a burnishing, or othersuitable, tool for giving the cusp-portion of the crown the properconformation.

If desired, the crown may be formed by applying the closed end of thecap to a dieplate, such as that represented in part at 26, when the cap25 is positioned on the former 20 as described, and thereupon strikingthe upper end of the plunger 24 a light blow, which will cause the cap25 to be drawnto a shape conforming to the shape of the end 22 of theformer with cusp-portions formed thereon produced by forcing the plungerinto the particular die in the die-plate to which the cap was applied,the different dies on the plate 26 permitting the operator to formcuspportions on the cap 25 of any shape desired, the operator in thusselecting the die for coiiperation with the plunger, being guided by theshape of the tooth which, with the one to be crowned, forms a pair.After the crown has been formed the plunger may be readily withdrawnfrom the former 20, whereupon the end 22 of the former contracts tonormal condition as represented in Fig. 5, permitting the crownindicated at 27 to be readily removed from the former. Should the crown27 for any reason require to be re-shaped, it may be readily replaced onthe former 20 and the operation just described be repeated until thecrown has been shaped as desired, the ductility of the metal of the cappermitting of the re-shaping thereof without impairment. In theoperation of reshaping the crown 27, when desired, a hand burnishingtool(not shown), may be used for bending the metal of the cap to produce thedesired conformation of the crown, the former 20 in this operationserving to readily support the crown and prevent it from collapsing.

After the crown has been shaped as de sired, it is preferred that asmall quantity of relatively hard solder be dropped into the invertedcrown to thicken the cusp-portion thereof so that it will stand the wearto which it is subjected in use.

In Fig. 8, I have illustrated a cap made from a piece of suitable metal,suchas 22 carat gold, bent to thimble form, instead of drawn, as in thecase of the cap 25. The cap of Fig. 8 may be formed from the rectangularsheet of metal indicated at 28 in Fig. 7 In practice, the sheet would beof a length corresponding to the circumference of the stub of the toothto be crowned and the sheet bent to the form illustrated in Fig. 8,whereupon the ends of the strip would be braised or .soldered togetherat their meeting edges indicated at 29. An edge of the tube thus formedshould be slit in preferably four places and the free ends thus bent tothe overlapping condition represented in Fig. 8. The cap thus producedis then ready to be formed into the crown illustrated in Fig. 9. Afterthe crown of Fig. 9 has been formed, the overlapping edges of the metalforming. the cuspportion of the crown should be soldered and smoothedoff.

My invention also has great utility in the manufacture of porcelaincrowns. In this case the shell-crowns formed as hereinbefore described,should be of metal the melting point of which is higher than the fusingpoint of porcelain, these shell crowns affording with matriceshereinafter described, molds into which the porcelain may be introducedand baked, the porcelain crown thus produced corresponding to thecontour of the inner, and consequently theouter, surface of theshell-crown. In this operation, the tooth-stump to be crowned, 'afterthe enamel has been removed, should preferably be shouldered at or belowthe gum edge and a covering of sheet metal the same as that of which thecrown is made, should be burnished over the stump to form a matrix. The

matrix should then be removed and the shellcrown filled with wetporcelain, placed over the matrix, and the whole baked in an electricoven. After the porcelain has cooled, an opening should be made in theshellcrown at its occlusal. portion for receiving more wet porcelain andthe baking operation repeated, these alternate filling and bakingoperations continuing until the space between the matrix and theshell-crown, is completely filled with baked porcelain, whereupon theporcelain crown thus formed can be readily removed from the shell-crownin any suitable manner.

In Figs. 10 to 19 inclusive I have shown an embodiment of my inventionfor forming metal shell backings for porcelain crowns. The drawings showmeans for forming the shells for both anterior and posterior teeth.

Referring particularly to Figs. 10 to 15 in-' elusive, the former andplunger, corresponding with the former 20 and plunger 24 of Fig. 1, arerepresented at 30 and 31 respectively. The former in this case is shapedto conform as nearly as possible to a perfect incisor excepting inthickness, its front side being flat as represented at 32. The end 33 ofthe former is formed in sections 34 by slitting the metal thereof asrepresented at 35, thus adapting the end 33 of the former to be expandedunder the action of the plunger 31 when the latter is forced into theformer. The blank from which the crown is formed'is preferably in theform of a tapering tube represented at 36 and open at both ends, thistube being of any suitable ductile metal and into which the former isintroduced at its expansible end 33, as represented by the constructionshown in Figs. 1 and 2. The plunger 31, which conforms in shape to theincisor to be crowned, is then introduced into the larger end of theformer 30 and forced into intimate engagement with the sections 34, thuscausing the latter to spread apart and draw the tube 36 to a shapeconforming to that of the end 33 of the former 30, as shown in Fig. 10.Withdrawal of the plunger 31 from the former 3O permits the sections 34:to spring toward each other and thus the crown represented at 37 is freeto be withdrawn from the former 30. The crown 37 thus formed pre sents aflat side 38 to which the porcelain facing 39 is applied and held inplace, as by the fingers, while the operator inserts a burnishing-toolbet-ween the upper end of the crown and the former, preferably with theplunger inside of the former, and burnishes the crown to cause thegingival portion thereof to fit against the upper portion of theporcelain facing. The crown is thereupon secured to the flat surface 38of the facing, as by metal pins 40 carried by the latter and extendingthrough openings 41 in the fiat side 38 of the crown to the Wall ofwhich they may be soldered or otherwise fastened. After the facing 39has been secured to the crown, the metal of the upper and lower edges ofthe front portion of the crown may be burnished to make smooth thejoints represented at 42 and 43 between the facing 39 and the crown.While I prefer to employ a tube 36 open at both ends as the blank fromwhich to form the crown, it will be understood that a cap having aclosed end may be employed in lieu thereof. It will also be understoodthat the tube or cap may be of the variety formed by drawing the metalto shape and thus rendering it seamless, or formed from a sheet of metalthe edges of which are soldered together.

In Figs. 16 and 17 I have illustrated an embodiment of my invention forforming shell-crowns for porce1ainfaced bicuspids, the former andplunger represented at 44tand 15 respectively, being the same as thoserepresented at 20 and 24, excepting in thickness, the former 44 havingone side flattened to cause a crown formed thereon to be of lessthickness than the finished crown and present a flat side to receive aporcelain facing such as that represented at 46. Tn forming the crownfor a bicuspid, the dieplate 26 may be used as described of theconstruction shown in Figs. 1 to (3 inclusive, though the shaping of thecap upon the former 44 may be performed by a burnishing or othersuitable tool.

In practice, a former for each tooth, and a plurality of plungers ofdifferent sizes for cooperation with each former would be provided formaking crowns to fit all teeth and all sizes of the same. If desired,plun gers and formers varying slightly in conformation from perfectteeth may be provided for use where the crowns to be made vary from theshape of perfectly formed teeth, though by burnishing with tools ashereinbefore stated, the crowns formed from formers and plungersconforming in shape to perfect teeth, may be caused to present almostall of the irregularities found in teeth.

From the foregoing description, it will be manifest that the operationof forming crowns may be quickly and economically performed, the patientsaved much time and discomfort, and a high degree of work accomplished.Furthermore, by my improved means stretching of the band-portions of thecrowns, as is common in prior methods of manufacture, is prevented, thusinsuring the perfect fit of the crowns upon the toothstubs.

It is preferred that the plungers be formed of relatively soft metal,such as type-metal, held against expansion by a shell of relativelytough metal, such as copper, German silver or other suitable metal, asillustrated in the drawings, it being preferred that the plungers beformed by forming a tube of the desired shape and thereupon filling thetube with the desired molten metal. By thus forming the end of theplunger which extends into the former, impairment of the end of the capas by fracturing and the spreading or upsetting of the end of theplunger, is prevented.

- What I claim as new and desire to secure by Letters Patent, is

1. In a device for manufacturing crowns and the like, the combinationwith an expansible and contractible hollow former formed of relativelymovable sect-ions disconnected along lines corresponding to thedevelopmental lines of the tooth and adapted to be inserted into atubular blank from which the crown is to be formed, a plunger insertiblein the said former, said plunger having a terminal die face and beingprovided with means for expanding said former and shaping said blankwhen forced into said former.

2. In a device for manufacturing dental crowns and the like, thecombination with an expansible and contractible hollow former formed ofa series of resilient arms, separated on the developmental lines of thetooth, and adapted to be inserted into a tubular blank from which thecrown is to be formed, a plunger insertible in the said former, saidplunger having a terminal die face and being provided with means forexpanding said former and shaping said blank when forced into saidformer.

3. In a device for manufacturing dental crowns and the like, thecombination with an expansible and contractible hollow former formed ofa tube split at one end thereof on lines corresponding to thedevelopmental lines of the tooth to form sections adapted to be movedwith relation toeach other, said former being adapted to be insertedinto a tubular blank from which the crown is to be formed, a plungerinsertible in the said former, said plunger having a terminal die faceand being provided with means for expanding said former and shaping saidblank when forced into said former.

4. Means for the purpose set forth comprising, incombination, anexpansible and contractible former adapted to be inserted into a tubularblank fromwhich the crown is to be formed, and a plunger insertible intosaid former for expanding it and formed of an outer shell of relativelyhard metal and a core of relatively soft material operating to force theend of the blank into the depressions of a die-plate, for the purposeset forth.

5. Means for the purpose set forth comprising, in combination, anexpansible and contractible former adapted to be inserted into a tubularblank from which the crown is to be formed, and a plunger insertibleinto said former and formed of a shell of relatively hard metal, an endof which conforms generally to the shape of the cusp of a tooth, and acore of relatively soft material, for the purpose set forth.

JOHN M. GILMORE.

In presence of- VILLIAM B. DAVIES, WVILLIAM T. J ONES.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

' Washington, D. G.

